The present invention relates to a driving system composed of a motor and a differential mechanism and a vehicle using the driving system.
As a driving system for improving a fuel efficiency of an engine, there is known a hybrid vehicle which utilizes a driving force of a motor.
Although various kinds of hybrid vehicles such as a series type, a parallel type hybrid vehicles are proposed, there is proposed a series-parallel type hybrid vehicle which uses two motors and a planet gear.
For example, Japanese Patent Application Laid-Open No. 7-135701 discloses a method that a driving force of an engine is input to a planet gear, and a motor controls so as to drive the vehicle by a driving force obtained from an output axis of the planet gear. The method is characterized by that the engine assists the driving force from the motor directly linked to the output axis while part of energy of the engine generates electricity by a generator. Therefore, the engine can be always operated at a high efficiency and high torque range and the method also has a transmission function.
The above-mentioned method can provide a high efficiency engine-electric hybrid vehicle, but has a disadvantage in that the size becomes large because the motor is required as one of the components.
Further, there is another disadvantage in that the productivity is deteriorated because number of the components becomes large.
An object of the present invention is to provide a small sized and high productive driving system for an engine-electric hybrid vehicle which has a conventional motor-generator as described above.
A driving system in accordance with the present invention comprises an engine; a plurality of motor-generators; and a plurality of coaxial differential mechanisms, wherein rotating output axes of the plurality of motor-generators are disposed parallel to and opposite to a rotating output axis of the engine, and a distance Lf1 projected in an axial direction between an end in a side of the rotating output axis of a first motor-generator having the largest dimension in a direction of the rotating output axis among the plurality of motor-generators and an end in a side of the rotating axis of the engine is smaller than a distance Lfi (i=2, 3, . . . ) projected in the axial direction between an end in a side of the rotating output axis of each of the other motor-generators excluding the first motor-generator and the end in the side of the rotating axis of the engine.
Further, a driving system in accordance with the present invention comprises an engine; a plurality of motor-generators; and a plurality of coaxial differential mechanisms, wherein rotating output axes of the plurality of motor-generators are disposed parallel to and opposite to a rotating output axis of the engine, and a distance Le1 projected in an axial direction between an end in an opposite side of the rotating output axis of a first motor-generator having the largest dimension in a direction of the rotating output axis among the plurality of motor-generators and an end in a side of the rotating axis of the engine is larger than a distance Lei (i=2, 3, . . . ) projected in the axial direction between an end in an opposite side of the rotating output axis of each of the other motor-generators excluding the first motor-generator and the end in the side of the rotating axis of the engine.
Further, a driving system in accordance with the present invention comprises an engine; a plurality of motor-generators; and a plurality of coaxial differential mechanisms, wherein rotating output axes of the plurality of motor-generators are disposed parallel to a rotating output axis of the engine and in a side of a surface distant from the engine, and a distance Lf1 projected in an axial direction between an end in a side of the rotating output axis of a first motor-generator having the largest dimension in a direction of the rotating output axis among the plurality of motor-generators and an end in a side of the rotating axis of the engine is smaller than a distance Lfi (i=2, 3, . . . ) projected in the axial direction between an end in a side of the rotating output axis of each of the other motor-generators excluding a first motor-generator and the end in the side of the rotating axis of the engine.
Further, a driving system in accordance with the present invention comprises an engine; a plurality of motor-generators; and a plurality of coaxial differential mechanisms, wherein rotating output axes of the plurality of motor-generators are disposed parallel to a rotating output axis of the engine and in a side of a surface distant from the engine, and a distance Le1 projected in an axial direction between an end in an opposite side of the rotating output axis of a first motor-generator having the largest dimension in a direction of the rotating output axis among the plurality of motor-generators and an end in a side of the rotating axis of the engine is larger than a distance Lei (i=2, 3, . . . ) projected in the axial direction between an end in an opposite side of the rotating output axis of each of the other motor-generators excluding the first motor-generator and the end in the side of the rotating axis of the engine.
Further, a driving system in accordance with the present invention comprises an engine; a plurality of motor-generators; and a plurality of coaxial differential mechanisms, wherein rotating output axes of the plurality of motor-generators are disposed parallel to a rotating output axis of the engine, and a center of gravity of the motor-generator having the maximum weight is placed at a position lower than a center of gravity of each of the other motor-generators.
Further, a driving system in accordance with the present invention comprises an engine; a plurality of motor-generators; and a plurality of coaxial differential mechanisms, wherein rotating output axes of the plurality of motor-generators are disposed parallel to a rotating output axis of the engine, and a lowermost end of the motor-generator having the maximum volume is placed at a position higher than a center of gravity of each of the other motor-generators.
Further, a driving system in accordance with the present invention comprises an engine; a plurality of motor-generators; and a plurality of coaxial differential mechanisms, wherein the coaxial differential mechanisms are disposed so that straight lines passing through rotating axes of at least two of the coaxial differential mechanisms are parallel to each other.
Further, a driving system in accordance with the present invention comprises an engine; a plurality of coaxial differential mechanisms; and a first and a second motor-generators, wherein the plurality of coaxial differential mechanisms comprise a first coaxial differential mechanism connected to an output axis of the engine, an input and output axis of the first motor-generator and a vehicle driving axis; and a second coaxial differential mechanism connected to the output axis of the engine, an input and output axis of the second motor-generator and a vehicle driving axis, the first motor-generator and the second motor-generator being disposed on a single axis, an axis of the first differential mechanism connected to the input and output axis of the first motor-generator penetrating through an axis of the second differential mechanism connected to the input and output axis of the second motor-generator.
Furthermore, the present invention is a vehicle comprising any one of the driving systems described above.